DEPARTMENT    OF    COMMERCE. 

BUREAU  OF  STANDARDS. 

S.  W.  STRATTON,  Director. 


CIRCULAR  OF  THE  BUREAU  OF  STANDARDS. 

No.  105. 

[2d  edition.    September  18,  1922.] 

UNITED  STATES  GOVERNMENT  SPECIFICATION  FOR 
LIQUID  PAINT  DRIER. 


FEDERAL  SPECIFICATIONS  BOARD. 

STANDARD  SPECIFICATION  No.  20. 

This  specification  was  officially  adopted  by  the  Federal  Specifications  Board  on 
February  3,  1922,  for  the  use  of  the  departments  and  independent  establishments  of 
the  Government  in  the  purchase  of  materials  covered  by  it. 


CONTENTS. 

Page. 

1.  General i 

2.  Sampling 2 

3.  Laboratory  examination 2 

4.  Basis  of  purchase 4 

1.  GENERAL. 

This  specification  applies  both  to  straight  oil  drier — that  is, 
material  free  from  resins  or  ' '  gums ' ' — and  to  Japan  drier ;  that  is, 
material  containing  varnish  "gums." 

The  drier  shall  be  composed  of  lead,  manganese,  or  cobalt,  or 
a  mixture  of  any  of  these  elements  combined  with  a  suitable  fatty 
oil,  with  or  without  resins  or '^ gums,"  and  mineral  spirits  or  tur- 
pentine, or  a  mixture  of  these  solvents.  It  shall  be  free  from 
sediment  and  suspended  matter.  The  drier  when  flowed  on  metal 
and  baked  for  2  hours  at  100°  C.  (212°  F.)  shall  leave  an  elastic 
film.  The  flash  point  shall  be  not  lower  than  30°  C.  (85°  F.)  when 
tested  in  a  closed-cup  tester.  It  shall  mix  with  pure  raw  linseed 

7789°— 22 


y.  ..••"**•"•*  Circular  of  the  Bureau  of  Standards 

oil  in  the  proportion  of  i  volume  of  drier  to  1 9  volumes  of  oil  with- 
out curdling,  and  the  resulting  mixture  when  flowed  on  glass  shall 
dry  in  not  more  than  18  hours.  When  mixed  with  pure  raw  lin- 
seed oil  in  the  proportion  of  i  volume  of  drier  to  8  volumes  of  oil, 
the  resulting  mixture  shall  be  no  darker  than  a  solution  of  6  g  of 
potassium  dichromate  in  100  cc  of  pure  sulphuric  acid  of  specific 
gravity  1.84. 

NOTE. — Deliveries  will,  in  general,  be  sampled  and  tested  by  the  following  meth- 
ods, but  the  purchaser  reserves  the  right  to  use  any  additional  available  information 
to  ascertain  whether  the  material  meets  the  specification. 

2.  SAMPLING. 

It  is  mutually  agreed  by  buyer  and  seller  that  a  single  package 
out  of  each  lot  of  not  more  than  i  ,000  packages  be  taken  as  repre- 
sentative of  the  whole.  Whenever  possible,  an  original  unopened 
container  shall  be  sent  to  the  laboratory,  and  when  for  any  reason 
this  is  not  done,  the  inspector  shall  thoroughly  mix  the  contents 
of  the  container  sampled,  transfer  not  less  than  i  quart  to  a  clean, 
dry  glass  bottle  or  tin  can  which  must  be  nearly  filled  with  the 
sample,  securely  stoppered  with  a  new  clean  cork  or  well -fitting 
cover  or  cap,  sealed,  and  distinctly  labeled  by  the  inspector.  The 
inspector  should  take  a  duplicate  from  the  container  sampled  to  be 
held  for  check  in  case  of  dispute,  and,  when  requested,  should  take 
a  sample  for  the  seller. 

3.  LABORATORY   EXAMINATION. 

(a)  SEDIMENT  AND  SUSPENDED  MATTER. — Thoroughly  mix  the 
sample.  Fill  two  test  tubes  of  the  same  size  (15  cm,  or  6  inches) 
to  within  2.5  cm  (i  inch)  of  the  top  with  the  sample.  Stopper 
the  tubes  with  clean  corks.  Let  stand  for  24  hours.  Note 
whether  sediment  is  evident  in  the  tubes;  if  not,  shake  one  tube 
vigorously  and  compare  the  two  tubes.  If  they  still  look  alike, 
the  sample  is  considered  free  from  sediment  and  suspended  matter. 

(6)  COLOR. — Mix  2  cc  drier  and  16  cc  clear  pure  raw  linseed  oil 
that  complies  with  the  specifications  of  B.  S.  Circular  No.  82.  Dis- 
solve 6  g  of  pure  powdered  potassium  dichromate  in  100  cc  of  pure 
concentrated  sulphuric  acid  (specific  gravity  1.84).  Gentle  heat 
may  be  used  if  necessary  to  secure  a  perfect  solution  of  the  di- 
chromate. This  solution  should  be  freshly  prepared.  The  color 
comparison  shall  be  made  by  placing  the  i :  8  drier-linseed  oil  mix- 
ture and  the  dichromate-sulphuric  acid  solution  in  thin-walled 
glass  tubes  of  the  same  diameter,  1.5  to  2  cm  (fi  to  if  inch)  to 


U.  S.  Government  Specifications  for  Liquid  Paint  Drier.  '   "3' 

depths  of  at  least  2.5  cm  (i  inch)  and  comparing  the  depth  of 
color  by  looking  through  the  tubes  across  the  column  of  liquid  by 
transmitted  light. 

(c)  MIXING    WITH    LINSEED    OIL,    SETTING   TO   TOUCH,    AND 
DRYING. — Mix  i   cc  of  the  sample  and  19  cc  of  clear  pure  raw 
linseed  oil  that  complies  with  the  specifications  of  B.  S.  Circular 
No.   82.     Thoroughly  clean  a  glass  plate,  finally  washing  with 
benzol  and  drying.     Pour  a  portion  of  the  mixture  of  linseed  oil 
and  drier  over  this  plate  and  place  the  plate  in  a  vertical  position 
in  a  well- ventilated  room,  the  atmosphere  of  which  is  free  from 
products  of  combustion  or  laboratory  fumes.     Allow  the  remainder 
of  the  mixture  to  stand  for  2  hours.     No  sediment  or  precipitate 
should  appear.     At  i-hour  intervals  examine  the  film  of  oil  on 
the  plate  by  touching  it  lightly  with  the  finger  at  points  not  less 
than  2.5  cm  (i  inch)  from  the  edges.      If  the  film  still  has  the 
greasy  feel  of  fresh  linseed  oil,  it  has  not  set  to  touch.     If  the  film 
feels  tacky  and  adheres  to  the  finger,  it  is  considered  to  have  set 
to  touch.     If  the  finger  can  be  drawn  lightly  across  the  film  with- 
out the  oil  sticking  to  the  finger  or  the  surface  being  marred  by 
this  treatment,  the  oil  is  considered  dry.     In  case  the  test  shows 
time  of  setting  to  touch  or  drying  greater  than  8  and  18  hours, 
respectively,  a  second  test  shall  be  run  on  a  different  day  and  the 
average  of  the  two  tests  taken. 

(d)  NATURE  OF  BAKED  FILM. — Thoroughly  clean  with  benzol  a 
piece  of  bright  sheet  metal,  either  bright  sheet  iron,  tin  plate,  or 
terneplate.     Shake  the  sample  of  drier  thoroughly  and  flow  enough 
on  the  plate  so  that  a  space  at  least  7.5  cm  (3  inches)  wide  is  cov- 
ered.    Allow  the  plate  to  stand  in  a  vertical  position  at  room  tem- 
perature for  30  minutes  and  then  hang  in  an  oven  at  a  temperature 
of  100  to  105°  C.  (212  to  221°  F.)  for  2  hours. 

Remove  the  plate  from  the  oven  and  allow  it  to  stand  at  room 
temperature  for  not  less  than  i  hour.  Test  the  film  of  drier  with 
a  knife  blade  at  a  point  not  less  than  2.5  cm  (i  inch)  from  the  edge. 
If  the  film  powders  or  particles  fly  under  the  knife  blade,  it  will  be 
considered  brittle,  which  will  be  cause  for  rejection. 

(e)  FLASH  POINT. — Determine  with  either  the  "Tag"  or  Elliott 
closed-cup  tester.     The  former  is  preferred.1 

1  Directions  for  using  the  Tag  tester  may  be  found  in  A.  S.  T.  M.  Standards  D  56-21,  and  directions  for 
using  the  Elliott  cup  in  Proceedings  A.  S.  T.  M.,  1917,  pt.  i,  p.  414. 


A  Circular  of  the  Bureau  of  Standards 

4.  BASIS  OF  PURCHASE. 

Drier  shall  be  purchased  by  volume,  the  unit  being  a  gallon  of 
231  cubic  inches  at  15.5°  C.  (60°  F.).  The  volume  may  be  deter- 
mined by  measure  or,  in  case  of  large  deliveries,  it  may  be  easier  to 
determine  the  net  weight  and  specific  gravity  at  15.5/15.5°  C. 
(60/60°  F.)  of  the  delivery.  The  weight  per  gallon  in  pounds  can 
then  be  determined  by  multiplying  the  specific  gravity  by  8.33. 
The  net  weight  in  pounds  divided  by  the  weight  per  gallon  gives 
the  number  of  gallons. 


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